Why build a house extension?
Answering this question is always the first step I guess. For me, this has been an issue for many years! I live in a rather old house that does not have a downstairs inside toilet. There is one outside the rear of the house but for obvious reasons this does not get used much in the winter months!
Moreover, we lack a utility room where we can put a freezer and washing machine etc. etc.
If you look at the picture above, it would seem to make sense to pull down the existing external toilet and build a small extension that encloses the space between the back wall of the toilet and the door of the house. Although not a particularly large area, it would be more than adequate for our needs and would, hopefully, be not too complicated to build.
The roof height would be determined not by the toilet roof level but the level of the existing door porch rook that can be seen on the right-hand side of the picture.
The two pieces of wood show where the roof line of the extension would be and the outside wall of the extension. I will use measurements from these pieces of wood to determine the basis measurements of the extension - so it's pretty important to get them right!